1. Field of the Invention
The present invention relates to a magnetic apparatus and a method of manufacturing the magnetic apparatus.
2. Description of the Prior Art
One application where a magnetic apparatus may be used is in vehicles equipped with a power steering assembly, such as the power steering assembly disclosed in U.S. Pat. No. 5,445,240 to Cunningham, et al. The power steering assembly includes a stub shaft and a retaining hub mounted to the stub shaft. The magnetic apparatus includes a magnet attached to the retaining hub and with the magnet defining a longitudinal axis. The magnet includes an outer surface and an inner surface opposing each other. The magnet further includes a first end wall and a second end wall adjacent the inner and outer surfaces. The first end wall defines a plurality of v-shaped notches extending axially relative to the longitudinal axis with the inner surface of the magnet includes a lip proximal to the v-shaped notches.
A method of manufacturing the magnetic apparatus includes forming the magnet with the v-shaped notches disposed in the first end wall. Grinding or machining of the inner surface of the magnet is required to form the lip on the inner surface. It is difficult to grind or machine features into the magnet because the magnet is very brittle and susceptible to cracking and damage. Thus it would be beneficial to eliminate the lip on the inner surface because forming the lip is expensive for production.
The retaining hub is formed by injection molding plastic in a mold cavity and when the plastic cures, the first end wall of the magnet is attached to the retaining hub. More specifically, plastic is disposed in the v-shaped notches and around the lip to attach the magnet to the retaining hub. The plastic shrinks around the lip and in the v-shaped notches to eliminate clearance between the magnet and the retaining hub.
Therefore, there remains a need to develop a magnetic apparatus and method of manufacturing the magnetic apparatus that eliminates the lip of the prior art design.